Trichophytid rash is a secondary allergic inflammatory reaction of the skin to infected dermatophytes. The primary infection focus is mostly caused by zootropic fungi, and the inflammatory reaction is strong, such as kerion, macerated erosive type or sweat blister type tinea pedis, etc. Trichophyton thunbergii can also cause trichophytid rash. Local fungal metabolites are antigenic and reach the skin through blood circulation, causing allergic reactions in the whole body and local skin. This secondary rash is negative for fungal examination and positive for trichophyton test. As the primary fungal infection focus is cured, the rash gradually disappears. Erythema, papules or blister lesions suddenly occur on the skin around the active lesions of the original dermatophytosis or on the skin far away from the lesions, often accompanied by itching. The skin lesions are non-specific and often dominated by a certain form. There is a primary fungal infection focus, the rash site is negative for fungi, and the trichophyton test is positive. The diagnosis can be confirmed by excluding similar diseases. Systemic treatment Oral antihistamines can be used for patients with systemic symptoms.